Buick Regal: Adaptive Forward Lighting Malfunction
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
- Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
Diagnostic Fault Information
1. Adaptive Forward Lighting Malfunction
Circuit/System Description
Battery positive voltage is applied to the headlamp control module at all
times. The headlamp control
module has a normal operational voltage range of about 12.5 - 16 V and is only
fully functional with the ignition switch is in the RUN position and the
headlamp switch in the AUTOMATIC LIGHT position.
The communications enable signal from the body control module (BCM) wakes the
headlamp control
module microprocessor. The headlamp control module receives serial data messages
from the engine
control module (ECM), transmission control module (TCM), electronic brake
control module (EBCM),
and BCM with information regarding power mode, speed, steering angle,
transmission gear selection,
and headlamp switch status. The headlamp control module calculates the headlamp
angle and sends
commands to the left and right adaptive forward lighting system headlamp
actuators. The headlamp
actuators drive the headlamps to the position commanded by the headlamp control
module. The
headlamp control module monitors the headlamp actuator motor control circuits
for proper circuit
continuity and for shorts to ground or voltage. If a malfunction is detected, a
DTC will be stored in
memory and the driver will be notified with a message displayed over the driver
information center
located on the instrument cluster.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Testing
1. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the
appropriate E13
Headlamp Assembly. It may take up to 2 min for all vehicle systems to power
down.
2. Test for less than 15 Ω between the ground circuit terminal 8 and ground.
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 15 Ω
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 6 and ground.
- If the test lamp does not illuminate
- Ignition OFF, disconnect the X1 harness connector at the X50A Fuse Block
- Underhood.
- Test for infinite resistance between the B+ circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the X50A Fuse Block - Underhood.
- Go to next step: If the test lamp illuminates
5. Test or replace the K26 Headlamp Control Module.
6. Ignition ON.
7. Verify the appropriate headlamp operates to the LEFT and RIGHT positions when
commanding
the appropriate Headlamp Horizontal Motor LEFT and RIGHT with a scan tool.
- If the headlamp does not operate LEFT and RIGHT
Test or replace the E13 Headlamp Assembly.
- Go to next step: If the headlamp operates LEFT and RIGHT
8. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Headlamp Replacement
- Control Module References for headlamp control module replacement,
programming, and setup
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Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
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Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
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1. Cornering Lamps Malfunction
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of
SEE MORE:
If equipped with Adaptive Cruise
Control (ACC), it allows for selecting
the cruise control set speed and
following gap. Read this entire
section before using this system.
ACC uses a radar sensor to detect
other vehicles. The
following gap is the following time
(or distance) between your vehicle
and
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
DTC Descriptor
DT